package com.prj.ufdm.cloud.svr.gateway.filter;

import java.util.ArrayList;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.cloud.gateway.filter.NettyWriteResponseFilter;
import org.springframework.core.Ordered;
import org.springframework.http.HttpHeaders;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

public class CorsResponseHeaderFilter implements GlobalFilter, Ordered {
	
	@Override
	public int getOrder() {
		// 指定此过滤器位于NettyWriteResponseFilter之后
		// 即待处理完响应体后接着处理响应头
		return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER + 1;
	}

	@Override
	@SuppressWarnings("serial")
	public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
		return chain.filter(exchange).then(Mono.defer(() -> {
			exchange.getResponse().getHeaders().entrySet().stream()
					.filter(kv -> (kv.getValue() != null && kv.getValue().size() > 1))
					.filter(kv -> (kv.getKey().equals(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN) || kv.getKey().equals(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS)))
					.forEach(kv -> 
						{
							kv.setValue(new ArrayList<String>() {{add(kv.getValue().get(0));}});
						});
			return chain.filter(exchange);
		}));
	}
}
